Method and device for connecting adjacent objects equipped with holes to each other

ABSTRACT

A method is disclosed for connecting adjacent objects ( 1 ) such as paper rolls to each other, the method comprising the step of inserting a bushing ( 3 ) through the center bores of at least two adjacent paper rolls. The method is implemented by way of moving the parts of the bushing ( 3 ) formed by at least two parts in the bore of the objects relative to each other, whereby the parts are guided by the mating division surfaces (A, B) of the bushings, at least one of the mating surfaces having a spiraling shape, in the longitudinal axis direction of the bushing so that the outer diameter (U) of the bushing increases thus causing the bushing to expand tight in the center bores of the objects ( 1 ). The invention also concerns a device for connecting objects ( 1 ) to each other.

[0001] The present invention relates to a method for connecting adjacent objects equipped with holes, such as paper rolls, to each other, the method comprising the step of inserting a bushing through the center bore of two or more adjacent paper rolls. The invention also relates to a device suited for implementing the method, whereby the device comprises a bushing insertable through the center bores of adjacent objects to be connected to each other.

[0002] Accordingly, the field of the invention concerns the connection of objects equipped with holes to each other by way of their holes. Typical specimen of such objects are different kinds of product web rolls wound about hollow roll cores, such as paper, paperboard or plastic web rolls. Hence, the description of the invention given below is directed to the application of the invention in regard to paper web rolls.

[0003] A broad web of paper produced on a papermaking machine is divided into narrower webs on a slitter, whereupon the webs are wound on a roll core of multiple-ply paper layers, shortly called a core, into customer rolls. The width of the customer roll may vary in the range of 100 to 4000 mm and its diameter may be in excess of 1500 mm. Conventionally, the rolls are handled and transferred by rolling and transfer lifts in a horizontal position. Having a width of 100 to 400 mm, the handling of the rolls may be problematic inasmuch as their diameter-to-width ratio may vary from 3 to 10. In order to optimize the handling and packaging of such disc-like objects, they are preferentially manipulated in combined groups or pairs. However, the handling of rolls on conveyors, for instance, particularly at the crossover areas thereof, is problematic inasmuch as the rolls topple easily and do not generally rotate in the same pace. To overcome these complications, a number of narrower rolls are bound to each other in order to make them easier to handle.

[0004] Connecting the rolls with each other may take place, e.g., by winding a flexible plastic wrapper axially about the roll group or by binding the rolls with each other using narrow bands threaded trough the center bore of the axially aligned rolls. A plastic wrapper or band is difficult to use as it needs an extra manual operation or dedicated tools for winding/clamping. When a narrow band is used, also a protective corner piece is needed to prevent damage to the edge of the paper roll. Furthermore, plastic is a foreign material in a papermaking mill and its use is shunned due to the risk of having plastic scrap in the papermaking process.

[0005] Another technique known in the art for connecting rolls to each other is to place a bushing or rod through the aligned roll cores. The use of a bushing involves the disadvantage that insertion of the bushing into the center of the roll cores requires that the bushing must have an outer diameter slightly smaller than the inner diameter of the core center bore. However, this arrangement fails to keep the rolls tightly together. A connecting rod is even a worse solution in this respect. During transportation the rolls tend to separate from each other, whereby the connecting bushing or rod readily moves in the center bore of the rolls and may even become entirely dislodged from its position on the way. Concurrently, also one-sidedly cleaved bushings are used that mount tightly in the center bore. Not even such a cleaved bushing can at all times secure a group of rolls in a satisfactorily fashion together. Furthermore, the insertion of such bushings is difficult particularly when a greater number of rolls must be connected together. The removal of a tightly fitting bushing may be difficult at the end-user site as it may be swollen due to moisture, for instance.

[0006] Rolls connected to each other are generally packaged by wrapping about their periphery a number of wrapper turns whose edges are crimped against the heads of the package, whereupon headers are placed on the crimped wrapper edges. If the rolls are not tightly abutting each other, they may move inside the package, whereby stacking the rolls vertically above one another creates creases at the abutment lines of the rolls. During the handling and transport of the rolls in their package, damage may occur readily if the rolls and their packages are not abutting tightly.

[0007] Generally, the narrowest web rolls resembling discs are packaged by piling the rolls on one another on a transport pallet with their flat side down, whereupon the rolls are packaged in a so-called shrink wrapper and then handled as palleted unit loads. A disadvantage of this kind of packaging is that a separate workstep is needed to pile the rolls. Moreover, transport pallets are expensive and become waste material after use.

[0008] It is an object of the present invention to provide a method for connecting adjacent objects equipped with concentric holes to each other. The method is characterized in that the parts of a bushing formed by at least two parts are moved in the interior bore of the objects relative to each other, whereby the parts are guided by the mating division surfaces of the bushings, at least one of the mating surfaces having a spiraling shape in the longitudinal axis direction of the bushing, so that the outer diameter of the bushing increases thus causing the bushing to expand tight in the center bores of the objects.

[0009] To implement the method, there has been accomplished according to the invention a bushing device characterized in that the bushing is comprised of at least two separate parts cooperating with each other at mating division surfaces of the bushing device, whereby at least one of the mating surfaces is at least partially spiraling.

[0010] Specifications of preferred embodiments of the invention are disclosed in the dependent claims of the present application.

[0011] Inasmuch as the method and device according to the invention makes it possible to connect objects in a reliable fashion to each other, it may advantageously be used for objects larger than those customarily packaged together in the art. Resultingly, the unit loads being handled may be made larger, whereby also the packaging and handling capacity of production systems is enhanced and operating costs are decreased respectively. By way of using the same material (claim 9) for fabricating both the device and the center core of the object, the manufacture of these elements can be arranged to take place at the site thus achieving benefits in both production and logistics. The cores are advantageously connected to each other by means of the present devices (bushings) already in conjunction with the manufacture of the center cores or, alternatively, prior to the winding of the paper web, whereby no extra workstep is needed for connecting the paper web rolls to each other after winding. Having the bushing and roll core made from the same material, they may also be disposed of or recycled together.

[0012] Next, the invention is described in detail with the help of preferred exemplary embodiments by making reference to the appended drawings in which

[0013]FIG. 1 is a partially sectional view of adjacently grouped objects (e.g., paper rolls) connected to each other according to the invention;

[0014]FIG. 2 is an enlarged view of two objects connected to each other by means of bushing having a shorter length (L₃);

[0015]FIGS. 3 and 4 illustrate a device according to the invention developed in a plane in order to elucidate the shape of the mating surfaces and the function of the device; and

[0016]FIG. 5 is a partially sectional view of another exemplary embodiment of the device according to the invention.

[0017] In FIG. 1 is shown a group of adjacently placed, substantially concentric objects such as paper rolls 1 to be connected to each other. While the objects discussed below are generally referred to as paper rolls, any other objects of the like kind may as well be connected to each other by virtue of the method according to the invention. Each one of the paper rolls is provided with a hollow core 2 having a device 3 according to the invention inserted through its center bore for connecting the paper rolls 1 to each other. The device is formed by a bushing 3 divided into at least two parts in its longitudinal direction. The longitudinal division of the bushing into parts is accomplished so that at least one of the division surfaces A, B along which the parts mate with each other is made spiraling about the longitudinal axis CL of the device. Advantageously, the bushing 3 is made from the same material as the roll core 2 on which the web material is wound.

[0018] At the instant being inserted into the bore of the roll core 2, the bushing 3 is in a so-called initial state where the outer diameter U of the bushing is smaller than the inner diameter of the core bore D, thus allowing easy insertion of the bushing through the bores of the cores 2 of the objects to be connected to each other. The length of bushing 3 is made such that it spans all the bores of the adjacent paper rolls 1. The different parts of bushing 3 are next moved relative to each other axially in directions of forces Fc under the guidance of the spiralingly mating division surfaces, whereby the outer dimension of the bushing increases by dU and the bushing locks in the center bore D of paper rolls 1 being connected smoothly expanding in direction Fd over its entire length. This wedged locking is elucidated in FIGS. 3 and 4 illustrating the bushing developed into a plane. The bushing connects the paper rolls 1 to each other and locks them together. As the force holding the rolls together is a function of the connecting force Fc, the wedge angles α, β, ζ and the friction therebetween, these parameters may be optimized readily by experimental techniques. To separate to rolls from each other, the mating parts of the bushing 3 need only to be pushed apart by a separating force applied in direction Fo. If so desired, a separated bushing may be reused.

[0019] The maximum length L_(1;2) of bushing 3 is advantageously made substantially equal to the height H_(1;2) of the triangle formed by the bushing division surfaces A, B, C or possibly slightly larger. The design of the bushing may be a so-called two-headed type, whereby the bushing is comprised of three parts and its wedging into a locked position takes place from two opposite directions. Then, the length of the bushing must be made respectively larger to be L₁+L₂. The length of the bushing may also be made such that it extends over a portion L₃ of the maximum allowable length of the bushing as illustrated in FIG. 2. Obviously, the length of the bushing must at all times be made compatible with the length of the roll group to be connected.

[0020] In the alternative embodiment of the invention shown in FIG. 5, the spiraling division surface of the bushing is made sectionally stepped. Thus, the overall length of neither the bushing 3 nor rolls 1 to be connected to each other is limited and, moreover, the wedged locking of the bushing takes place uniformly expanding to diameter Fd over the entire length of the center bore of the paper rolls. In this embodiment, the separation of the rolls from each other occurs easily by moving the parts of bushing 3 at their ends into a direction Fo opposite to that employed during the wedged locking. The embodiment of FIG. 5 is advantageous when packing involves roll groups of different lengths, whereby the structure of bushing 3 allows its length to be trimmed to cope with the length of the roll groups being connected. Herein, the bushings 3 are advantageously first produced in long sections, whereupon their trimming to desired length can be made in conjunction with the trimming of the roll cores. Thus, the fabrication of the bushings can be arranged to take place automatically along with the manufacture of the roll cores.

[0021] The above description of the method and device according to the invention was related to certain preferred embodiments for connecting paper, paperboard and plastic web rolls to each other. However, the invention is not limited to those exemplary embodiments, materials or applications, but rather, any application entangled by the scope and spirit of the appended claims must be understood to be covered by the claims. Accordingly, the method and device according to the invention can be used for connecting to each other and disconnecting from each other any type of object, tubular article, piece of machinery and the like equipped with concentric bores. The force required for clamping the bushing in place or dislodging from such a state can be imposed on the bushing device by means of any suitable implement as is obvious from the above description to a person skilled in the art. Naturally, the insertion of the locking device may be accomplished entirely automatically with the help of a robot, for instance. 

What is claimed is:
 1. A method for connecting adjacent objects (1) equipped with holes, such as paper rolls, to each other, the method comprising the step of inserting a bushing (3) through the center bores of at least two adjacent paper rolls, characterized in that the parts of the bushing (3) formed by at least two parts are moved in the interior bore of the objects relative to each other, whereby the parts are guided by the mating division surfaces (A, B, C) of the bushings, at least one of the mating surfaces having a spiraling shape in the longitudinal axis direction of the bushing, so that the outer diameter (U) of the bushing increases (by dU) thus causing the bushing to expand tight in the center bores of the objects (1).
 2. The method of claim 1, characterized in that, to clamp the bushing (3), a tool is used for imposing an axially aligned force (Fc) on the bushing inserted into the center bores of said objects so that the force works on at least one end of the bushing, advantageously on both ends thereof.
 3. A device for connecting adjacent objects (1) equipped with holes, such as paper rolls to each other, the device comprising a bushing (3) insertable through the center bores of said adjacent objects (1) to be connected to each other, characterized in that said bushing (3) comprises at least two separate parts cooperating with each other at the mating division surfaces of said parts, whereby at least one of the mating surfaces (A, B, C) formed between said parts is made at least partially spiraling.
 4. The device of claim 3, characterized in that the spiraling division surface(s) of the bushing (3) is/are divided into section(s) and the division is made in a stepped fashion.
 5. The device of claim 3 or 4, characterized in that one (A) of the mating division surfaces of the bushing (3) is made spiraling while the other one (B) is aligned parallel to the longitudinal axis of the bushing.
 6. The device of claim 3 or 4, characterized in that the mating division surfaces of the bushing parts are adapted to spiral in mutually opposed directions, whereby their wedge angles (β, ζ) can be equal or unequal.
 7. The device of claim 3 or 4, characterized in that the mating division surfaces of the bushing parts are adapted to spiral in the same direction, whereby their wedge angles aligned in mutually opposed directions.
 8. The device of any one of claims 3-7, characterized in that said bushing (3) is made two-headed and divided in three parts, whereby the bushing clamping force (Fc) is applied from two directions.
 9. The device of any one of claims 3-7, characterized in that said bushing (3) and the center cores (2) of the objects to be joined are of the same material. 